Silicon is widely used as the material of choice for semiconductor and insulator applications in nanoelectronics, micro-electro-mechanical systems, solar cells, and on-chip photonics. In stark contrast, in this paper, we explore silicon’s metallic properties and show that it can support propagating surface plasmons, collective charge oscillations, in the extreme ultraviolet (EUV) energy regime not possible with other plasmonic materials such as aluminum, silver, or gold. This is fundamentally different from conventional approaches, where doping semiconductors is considered necessary to observe plasmonic behavior. We experimentally map the photonic band structure of EUV surface and bulk plasmons in silicon using momentum-resolved electron energy loss spectroscopy. Our experimental observations are validated by macroscopic electrodynamic electron energy loss theory simulations as well as quantum density functional theory calculations. As an example of exploiting these EUV plasmons for applications, we propose a tunable and broadband thresholdless Cherenkov radiation source in the EUV using silicon plasmonic metamaterials. Our work can pave the way for the field of EUV plasmonics.

中文翻译：

---

硅中的极端紫外线等离子体和Cherenkov辐射

硅被广泛用作纳米电子，微机电系统，太阳能电池和芯片上光子学中半导体和绝缘体应用的首选材料。与之形成鲜明对比的是，在本文中，我们探索了硅的金属特性，并表明它可以支持传播的表面等离激元，集体电荷振荡，并且在其他等离激子材料（如铝，银或金）无法实现的极端紫外线（EUV）能量范围内。这从根本上不同于传统方法，在传统方法中，掺杂半导体被认为是观察等离激元行为所必需的。我们使用动量分辨电子能量损失谱，通过实验绘制了EUV表面和体等离激元在硅中的光子能带结构图。我们的实验观察结果通过宏观电动力电子能量损失理论模拟以及量子密度泛函理论计算得到了验证。作为利用这些EUV等离子体激元进行应用的示例，我们提出了使用硅等离子体超材料的EUV中可调谐且宽带的无阈值Cherenkov辐射源。我们的工作可以为EUV等离子体技术领域铺平道路。